Feed device for flying shear



United States Patent 72] Inventor John 0. Richards Mentor, Ohio [21] Appl. No. 787,961

[22] Filed Dec. 30, 1968 [45] Patented Dec. 1, 1970 [73] Assignee Production Machinery Corporation Mentor, Ohio a corporation of Ohio [54] FEED DEVICE FOR FLYING SHEAR 1,861,554 6/1932 Sheperdson et al 83/288 1,900,252 3/1933 Morgan 83/288 2,634,811 4/1953 Schaelchlin 83/288X 2,692,361 10/1954 Asbury et al 83/288X Primary Examiner-William S. Lawson Attorney-Meyer, Tilberry and Body ABSTRACT: An apparatus for shearing a coil of strip material into sheets of predetermined length wherein the strip material is fed by a pair of pinch rolls to a flying shear machine. To obtain a maximum number of sheets from the coil, a minimum first cut is made. To minimize the length of the first cut, the shear is stopped at a predetermined point in its cycle between cutting strokes, and is restarted when the strip end advances at thread speed to a position a predetermined distance from the shear. The point in its cycle at which the shear is stopped is dependent upon the predetermined distance, the thread speed of the strip end as it advances into the shear, and the shear acceleration rate from stop.

PINCH F ROLLS% 52 l f r 3a D.C.DR|VE {D so MOTOR 54 SPEED 32 REG.

34 GEN-y GEN) /36 SHEAR 56 AR SPEED REG.

62 42 I 46 1 REF. VOLT RAMP 64 THREAD SPEED FUNCTION 44 GENEFZATOR RUN SPEEDS- Pate atoll De c. l, 1970 I Sheet L of 5 I I'NVENTOR. V JOHN o. RICHARDS ATTORNEYS V Pam! Dec. 1,1971: 3,543,624

Sheet of 5 FIG. 2 I

1 v ll j MIME INVENTOR. JOHN O. RICHARDS 1 BY llfwjdeuq bady ATTORNEYS Patented Dec. 1,- 1970 3,543,624

Sheet 'L of 5 v l4 l a2. PINCH 20 U s2 g? C OE l PHOTOCELL i (TACH r "TACH Y PULSE N Q: I 6O GENERATOR 5o 38 ,A 1 sHEAR IMOTQR TlooRnvE 5e DIGITAL MOTOR 54 v 48 COUNTER 32 SPEED STOP\ R sHEAR 34 A Y es (PRESET GEN) o o-+- SW'I T'Z HNG SHEAR SHEAR 'SPEED REG.

RESTART P THREAD s EED F v N I 44 GENEFEATOR I RUN SPEED;

FIG. 3

t3 RUN EA 0 L B, C D g s THD. A I COUNTER i I (SET) 1 (LS. CLOSURE LDIG. \PHOTO' 4 FIRST PRESET v TIME SIGNAL sac-mm... CUT

INVENTOR.

FIG 5 JOHN o. RICHARDS ATTORNEYS 1 6 REF. vour I RAM FEED DEVllClE FUR FLYING SHEAR DESCRIPTION back and forth in the direction of movement of the strip 7 material. The length of the sheets cut from the coil is adjusted by causing the shear to make a plurality of miscut revolutions between each cutting stroke, and by selecting the proper ratio of rates of movement of the shear drive and feed rolls, the effective length of each sheet being a multiple of the number of miscuts and a function of this ratio. One flying" apparatus which can be used with the invention is what is called the Hallden Shear.

For purposes of this application, the shear cycle shall be defined as the interval between the shear cutting strokes, the cycle encompassing an adjustable but preset number of miscut revolutions. v

The problem experienced with such a cutting apparatus is that of minimizing the length of first cut or the length of the crop end taken in the first cut. With a minimum first cut, it is possible to obtain the maximum number of sheets of desired length from the coil of strip material without taking excess scrap at opposite ends of the coil. However, complex systems have heretofore been required to time the advance of the strip material with the moving shear so that a first cutting stroke is made just after the strip end passes through the shear knives.

An object of the present invention is to provide a new and improved method and apparatus for timing the advance of the strip material with the moving shear so that the length of the crop end or first cut is minimized.

In accordance with one aspect of the present invention, there is provided a method for shearing a coil of strip material comprising the steps of stopping the shear at a predetermined point in its cycle between cutting strokes, and then feeding the strip material into the shear at a predetermined thread speed, which is slower than normal run speed for the machine. The advancing end of the strip material is detected at a point a predetermined distance from the shear, at which time the shear is restarted. The point in its cycle at which the shear is first stopped is dependent upon the thread speed of the strip end into the shear, the location of the detection point, and the rate at which the shear accelerates from stop, the thread speed and the distance of the detection point ahead of the shear being such that the end of the strip material passes in the remaining part of the shear cycle a minimum distance through the shear knives as the knives close in a first cutting stroke.

In a preferred embodiment in accordance with the invention, acounter is coupled to feed rolls ahead of the shear. As there is an exact rotational distance covered by the feed rolls for a given cycle or cut-length setting of the shear, the counter may be set to stop the'shear at a predetermined point in the shear cycle. An electrical circuit functions to bring the shear to a controlled and precise stop in response to the counter signal, and then to reaccelerate the shear and advance the coil of strip material at thread speed into the shear. Following the first crop end cut, the shear machine is caused to further accelerate to run speed.

The invention and advantages thereof will becomemore apparent upon consideration of the following specification, with reference to the accompanying drawings, in which FIG. 1 is a schematic elevation partial section view of a shear machine in accordance with the invention;

FIG. 2 is a plan view of the machine of FIG. 1;

FIG. 3 is a schematic electrical block diagram illustrating the arrangement of electrical components with the shear machine of FIG. 1;

FlGS. and 3A show an electrical circuit diagram for operating the shear machine of FIG. 1 in accordance with the present invention; and

FIG. 5 is a graph illustrating the method in accordance with the invention by which the shear machine of FIG. 1 is preset.

Referring to the drawings, particularly FIGS. l and 2, there is illustrated a l-lallden shear machine 12, an item well known in the art, ahead of which are disposed shear leveler rolls l4. Feed rolls 16 and 18 are disposed on opposite sides of the leveler rolls. The purpose of the leveler rolls is to flatten the strip material which is in a partly sinusoidal shape following uncoiling of the strip from a coil of material (not shown). The feed rolls feed the strip material at a predetermined thread speed through the leveler rolls and into the shear machine.

As shown in FIG. 1, the shear machine l2 reciprocates in a rocking manner on table 19 between its retracted position shown in solid lines and forward position (not shown), cutting the strip of material into sheets at a predetermined point during forward movement of the machine. In a manner which is well known and not part of this invention, the shear machine has a certain cycle utilizing a predetermined number of miscut strokes which along with the ratio of rates of movement of the shear drive and feed rolls, determines the length of each sheet cut from the coil of strip material.

Further removed from the shear machine in the direction of feed there are disposed pinch rolls Zil, the speed of which is timed with the feed rolls. The pinch rolls take the strip material from the coil and feed it to the shear feed rolls. Between the pinch rolls and the feed rolls, there is disposed a photocell device 22 designed to detect the end of the advancing strip coming from the pinch rolls, and start the shear machine in accordance with a procedure to be described.

Referring to FIG. 3, the overall arrangement of electrical components in combination with the drive system of the invention is schematically illustrated: In this FIG, the pinch rolls 2@ are shown ahead of the shear l2, and between the pinch rolls and the shear are the feed rolls 16, 1 and leveler rolls M. The photocell 22 for detecting the advancing end of the coil of strip material is shown located between the pinch rolls and the feed and leveler rolls. A main drive motor 30 operates the shear and the leveler roll stand, as well as the feed rolls at opposite ends of the leveler roll stand, via the main drive box 31 and roll drive box 33 (shown in FIG. 2). In this way, all of these components are mechanically connected to operate at the same speed. The main drive motor is a dc motor provided with current by a dc adjustable voltage generator 32, having a voltage output which is regulated via generator field 34 by a shear speed regulator 36. The regulator in turn is responsive to a feedback speed signal from tachometer 38 (recording the drive speed of motor 30) and a reference voltage signal from a ramp function generator 40. These two signals are compared by the speed regulator so that the speed of the shear machine is held at a value corresponding to the reference voltage output from the ramp function generator.

The ramp function generator in turn is responsive to a signal from an input switching circuit 42, the output of the latter being dependent upon the setting of a run speed variable resistance potentiometer 44 or, alternately, a thread speed potentiometer 46. As will be described, the machine thread speed is less than the machine normal run speed, and is used only for presetting the shear machine, feeding the strip materival into the shear and making the first crop end cut. Activating the input switching circuit is a shear preset button 66 and a stop signal received from digital counter 48. The latter receives a pulse counting signal from pulse generator Ml, and counting is commenced by a start-count signal received from shear switch $2, which is closed at each cuttingstrolte of the shear blades. In this way, counting begins or commences following a cutting stroke of the shear blades. Also activating the input switching circuit is a signal received from photocell 22.

The pinch rolls 20 are driven by a separate motor drive unit 54 by means of as input from d.c. generator 56, the output of the latter being controlled by speed regulator 58. To the re gulater 58 is fed a speed feedback signal from tachometer 60 and two reference signals from thread speed potentiometer 62 and run speed potentiometer 64,- these potentiometers being mechanically connected to the corresponding potentiometers 46 and M for the main motor 30 so that the surface speed of the pinch rolls equals the surface speed of the feed rolls l6 and 18. In this way the pinch roll rotational speed will also correspond to the speed of the shear.

In operation, referring to FIG. 5, in conjunction with FIG. 3, the shear preset button 66 is operative through the input switching circuit to start the shear running at thread speed (points A to B, FIG. The shear limit switch 52 records a cutting stroke and initiates counting by the digital counter 48 (point C of FIG. 5), which after a selected number of pulses from the pulse generator 50 or portion of the shear cycle, activates the input switching circuit to bring the shear to a stop (points D to E). So that the stop is controlled, i.e., that the location of the shear machine at stop is precise, the ramp function generator functions to ramp the machine down to stop at a controlled deceleration rate. In this way the shear machine is preset accurately at a precise location in its cycle.

Following stopping of the shear at point E, the motor 54 is started feeding the strip material in the direction of the shear at the thread speed set by potentiometer 62. The strip material is up to thread speed when its advance end passes beneath photocell 22 causing the latter to provide a signal to the input switching circuit 42 restarting the shear machine and accelerating it again to thread speed (points F to G, FIG. 5). The shear machine is then run at thread speed, control of the main motor at a thread speed corresponding to the thread speed of the pinch rolls being by means of the mechanical connection between the potentiometers 62 and 46. As the coil of strip material is advanced into the shear machine, the latter completes its cycle at point H and makes a first minimum out just as the strip of material passes through the shear blades.

Following point B, FIG. 5, the input switching circuit 42 is triggered (in a manner to be described) so that it becomes responsive at point I to an input from the run speed potentiometer 44 and the main drive motor 30 is increased to a normal run speed faster than thread speed. Prior to this point, the pinch rolls normally will have opened, when the coil of strip material becomes engaged by the feed rolls l6 and 18, so from that point on, the speed of the strip material is controlled by the feed rolls.

The significant adjustment by the operator of the shear machine in making a minimum first cut is setting the digital counter 48, i.e., selecting the number of pulses from the pulse generator, to bring the shear machine to a stop, prior to restart, at point E. Setting the digital counter to stop the shear at a predetermined preset point is accomplished by taking into consideration the distance of the photocell 22 ahead of the shear, the surface speed of the pinch rolls (or advancing thread speed of the coil of strip material) and the deceleration and acceleration rate of the shear; i.e., the rate at which the shear decelerates from thread speed and then reaccelerates to thread speed after restart.

It should be noted that the pinch rolls and the coil of strip material will be at corresponding thread speeds as the photocell signals the switching circuit, so that the acceleration and deceleration of the shear to and from thread speed is the only variable speed factor which has to be taken into account in calculating the counter setting; i.e., acceleration of the pinch rolls is not a factor which must be taken into account.

Details of the electrical control circuit including the switching circuit will now be described with reference to FIGS. 4 and @A. These FIGS. are for the main motor circuit only. Referring to FIG. 4, an ac. input coil 110 provides a voltage and current in line 1 which is transmitted via line 4 to the digital counter 48. Details of digital counters are well known. One suitable counter is that made by the Louis Allis Co., a counter of the bidirectional type with a single preset. It is identified as the Dynapar Digital Position Control System Counter type 215D. The purpose of the counter and asshear limit switch 52 (LS-1),

sociated components is to preset the shear prior to advancing the coil of strip material to the shear at thread speed.

For the purposes of illustration, the counter is shown schematically as containing a normally closed switch CR-l (H2) in line 4A opened in response to an output from a rely (not shown) in the counter. The counter is provided with input terminals which receive a signal or pulse from the pulse generator 50, which signal or pulse is operable through a signal gate to advance the counter to successive contacts. The counter is preset at a selected contact by the operator, and when the counter reaches the preset contact, the counter relay is energized opening the normally closed switch CR-l of line 4a the relay which in a manner to be discussed brings the shear machine to a stop).

Controlling the counter, and the point at which counting commences, is a startcounf circuit 114, line 3, connected to a second set of terminals on the counter, and containing a normally open switch PCR-3 (H16) and the normally open which are in series with each other. The start-count" circuit is connected to the counter signal gate, and its function is to turn on the counter so that it is responsive to pulses from the pulse generator. In the absence of an input from the start-count" circuit, and for such an input both switches PCR-3 and LS-ll must be closed, the pulse generator output does not advance the counter, and counting is delayed. In this way, the shear can be made to complete the. remainder of whatever cycle it was in, assuming it was previously stopped at an intermediate point in a cycle. At the completion of that cycle, the shear blades close, closing limit switch LS-l (52), which energizes the digital counter, and the shear is then run through the part of its next cycle to the counter set point selected by the operator.

Line 5 of the electrical circuit contains the shear preset switch 66 and also preset control relay PCR (124) which closes a normally open switch PCR-i (126) in line 4a, the same line which-contains counter relay switch CR-l (112); normally open switch PCR-2 (128) in line 7, and the normally open switch PCR-3 (116), mentioned above, in the shear limit switch or start-counter circuit of line 3.

Pressing the shear preset button 66 in line 5 transmits a flow of current through the preset control relay PCR (124), closing switches PCR-l (line 4a), PCR-Z (line 7), and PCR-3 (line 3). The flow of current inthe PCR relay is held by closing of switch PCR-l the current passing through the normally closed switch CR-l which is part of the digital counter. In a manner to be described, the closing of switch PCR-Z energizes the armature of the main drive motor 30 causing the latter to rotate. The switch also causes the dynamic brake for the shear machine to release. As the shear accelerates and then advances to execute a cutting stroke, the limit switch LS-l is closed turningthe counter signal gate on" and making the counter responsive to pulses from the pulse generator 50, in turn responsive to revolutions of the feed rolls (which are driven along with the shear). This advances the counter 48, until a preset point of the counter is reached, at which time the normally closed switch CR-l is opened, terminating the flow of current in the hold circuit for relay PCR, deenergizing the relay. This opens switch PCR-Z and stops the main drive motor in a manner which will be described. It also opens switch PCR-3 of the start-count" circuit turning the counter off.

It was mentioned that the main drive motor 30 was energized or started on closing switch PCR-2 and stopped on opening switch PER-2. This is accomplished as follows. With the flow of current in relay PCR in line 5, normally open switch PCR-Z in line 7 closes permitting a flow of current through thread control relay TCR (130) in line 6, which flow of current continues so long as switch ICR-Z remains closed. Relay TCR closes normally open switch TCR-li (132) in line 15, which switch is part of a rectifier circuit including a full wave bridge rectifier 134, in line 14, and relays DB (136) and M (138) in lines 16 and 17. These latter relays are energized when switch TCR-l is closed.

The motor armature 30 is part of a separate circuit in line 33 (FIG. 4A), in series withthe generator armature 32 (line 31), the latter being driven by an a.c. motor (not shown) and rotated within the influence of a generator field 34 (line 30) to provide a voltage and current to the motor armature. The relays Mand DB respectively close normally open switch M-l (item 140 in line 33) and open normally closed switch DB-1 (item 142 in line 34) to apply a voltage across the motor armature and to disconnect the dynamic brake resistor (item 43) with the motor armature, to brake the motor in a known manner when switch DB-l is closed.

The purpose of the rectifier 134 in line 14 is to provide a dc. current to the relays DB and M (which are d.c. coils) from the a.c. input coil 1% in lines 12, 13.

It was mentioned that following a predetermined count and travel of the shear machine, the counter switch CR-1 is opened interrupting the flow of current in relay PCR which in turn causes relays DB and M (lines 16 and 17) to open and close respectively motor switch M-1 and dynamic brake switch DB-l. This brings the machine to a stop, but it is important that the deceleration and stop be controlled so that the machine is precisely in the calculated-position of its cycle prior to restart.

1f the current to the motor 30 is terminated abruptly and if the dynamic brake is abruptly applied, there will be an indeterminate amount of drifting. To avoid this, the electrical circuit is provided with a hold relay GVR (146, line '32) in parallel with the generator armature, and with the ramp function generator 40 in line 23.

Turning first to the ramp function generator, the amount of voltage supplied by the armature 32 is a function of the field 34, which in turn is a function of the current flow transmitted through the full-wave rectifier 146 in line 29. Terminals of the rectifier are connected to an SCR Firing Unit148 which has two output windings 150 and 152 in line 27 controlling the voltage across the bridge 146 through gates SCR-l and SCR-2 (items 154 and 156 of line 29). The input windings in the SCR Firing Unit are a speed reference winding 158 in line 26 and a feedback winding 160 in line 25. The current through the feedback winding is a function of the tachometer speed (item 38) which is connected by a direct drive to the motor armature, so that the current through the feedback winding is in direct correspondence with the motor armature speed. A speed reference current in the speed reference winding 153 on the other hand is a direct reflection of the the output of the ramp function generator 40in line 23 of the circuit.

A characteristic of a ramp function generator is its ability to increase and decrease the voltage across its output terminals in response to termination of an input signal, in a time-voltage relationship. Accordingly, when switch CR-ll is opened, the voltage drop in winding 158 drops in a time-voltage relationship, causing a parallel drop in the generator field. In that the voltage drop across the bridge 146, or current in the generator field coil 34), is a function of the difference between the reference and feedback voltages, the motor 30 slows down at a rate corresponding to the time-voltage relationship of the ramp function generator output. I

The hold relay GVR (146) closes normally open switch GVR-l (164) in line 17 which is in parallel with switch TCR-l in line 15. Accordingly, even though switch TCR-l is opened with opening of switch CR-l in the preset circuit, switch (NR- 1 1 remains closed as long as the voltage across the generator armature 32 (and relay GVR) remains above a set value. This holds the motor switch M-1 (line 33) closed and the brake switch DB-l open for a period of time following the opening of relay CR-l.

When the voltage across armature 32 drops to a predetermined amount, relay GVR releases switch GVR-1 in line 17,

'cutting off the current to the motor and closing switch DB-1 to the dynamic brake, abruptly bringing the shear to a stop. By permitting the dynamic brake to bring the shear to a stop after the shear has been considerably slowed by the ramp function generator, the shear is preset at an exact location in its cycle.

The power supply for the ramp function generator is d.c. unit 162 in line 13, and the generator has a third input terminal which controls the magnitude of its output, the input terminal being alternately connected to one of two variable resistors or potentiometers, the thread speed potentiometer 66 in line 19, and the run speed potentiometer M, in line 21. Which potentiometer is connected to the ramp function generator depends upon whether relay switch TCR-Z (166) in line 20 or relay switch RCR-3 (168) in line 22 is closed. in the above example during the shear preset stage, switch TCR-Z is responsive to relay TCR in line 6 and is closed. Since the thread speed potentiometer 46 is set to produce a low reference current in winding 158 and a correspondingly low generator field, the speed of the shear motor will also below.

Referring again to FIG. 5, the principle of operation of the shear machine during the preset stage should now be clear. The preset button is depressed (point A on the FIG), and by virtue of the ramp function generator, the shear is accelerated to a desired thread speed (point B). After a number of cycles, the limit switch 52 (LS-1) is closed at point C, starting the digital counter. At point D, the counter relay causes (IR-1 to open, terminating the flow of current through switch TCR-2 (line 215). However, the voltage output of the ramp function generator decreases in a time-voltage relationship, and by virtue of relay GVR (holding switch M-l closed and switch DB-1 open), the motor 30 slows to point E in a controlled stop. lust short of full stop the shear brake is applied bringing the shear machine to a stop at a precisely known point in its cycle.

At this point,'the shear is preset. It is now necessary to advance the coil or strip material towards the shear machine, and this is accomplished by separately operating the pinch roll motors 54 at thread speed. As the end of the coil or strip material advances, the end is detected by photocell 22, activating normally open switch A (168) in line 8 of the electri; cal circuit for motor 30. This again energizes relay TCR-l (130), closing normally open switches TCR-l. (132, line 15) and TCR-Z (166, line 20) to start the main motor 30 and bring it again up to thread speed. At this point, the speed of the pinch rolls corresponds to the main motor speed by virtue of the mechanical connection between thread speed potentiometers 46 and 62.-

Assuming that the operator has accurately set the digital counter in accordance with the deceleration of the shear machine to its preset point, the thread speed, its reacceleration rate and the distance between the photocell and the shear point, the shear blades close on the coil end just after the coil is passed between the blades so that the first crop end cut is of minimum length.

At this point, the run button 170 (line 9 of the main motor circuit) is depressed by the operator. This energizes relay RCR (172, line 9) opening normally closed switch RCR-Z (174, line 6) terminating the How of current through relay TCR; closing normally open switch RCR-1 (176, line 16) permitting the flow of current through this switch to the motor and dynamic brake relays M and DB, and closing switch RCR- 3 (178, line 22) so that the ramp function generator output becomes a function of the setting of the run-speed potentiometer 44, increasing the generator field, the generator armature voltage, and the motor armature speed.

Alternatively a photocell 179, FIG. 1, can be employed to energize a relay (not shown) which closes contacts MC, line 10, FIG. 5, to automatically energize the run speed relay RCR.

ln an example in accordance with the invention, the thread speed potentiometer 46 may be set so that the thread speed is 100 feet per minute, whereas the run-speed potentiometer 44 is set so that the run speed is much higher in the order of about 400 feet per minute. The machine could be continued at thread speed, but the demands of higher production require the higher run speed.

The OL switch in line 5 (item is for overload, breaking the current through relays PCR, TCR and RCR in the event of an overload condition in the motor circuit. This would be detected by resistor CL 182 in the motor circuit (line 33).

Line 6 of the main motor electrical circuit also contains thread speed button 184 in the event the operator wishes to run the shear machine at thread speed independent of the digital counter or switch A (168, line 8) closed by photocell 22.

Although the invention has been described with reference to specific embodiments variations within the scope of the following claims will be known to those skilled in the art. For instance, instead of photocell 22, FIGS. 1 and 3, any strip-end detection device can be employed.

I claim:

1. A machine for shearing a roll of strip material into a plurality of sheets comprising in combination:

flying shear means;

feed roll means to feed said strip material to said shear means;

detection means to detect the advancing end of said strip material;

drive means for said shear means and feed roll means;

control means for said drive meansincluding a counter means the actuation of which is proportional to travel of said flying shear means, and circuit means which stops said shear means in response to a signal from said counter means at a precise point in the shear means cycle; and

said circuit means also being responsive to a signal from said detection means to restart said shear means when the advancing end of the strip material is at a set'distance from the shear means.

2. The machine of claim 1 wherein said circuit means is an electrical circuit including a ramp function generator, said drive means including a dc. motor, the electrical circuit further including a generator armature to provide a current flow for said motor, a generator field to induce a voltage in said armature, switching circuit means responsive to said counter means and detection means operatively connected through said ramp function generator to said generator field; the voltage drop across said generator field being ramped downwardly by said ramp function generator in response to a signal from said counter means.

3. The machine of claim 2 wherein said electrical circuit includes a relay in parallel with said generator armature, switch means actuated by said relay when a minimum voltage exists across said armature; said switch means being operatively connected to said motor to maintain a current therein until the voltage drop across said generator field is ramped to a minimum value.

4. The machine of claim 2 wherein said switching circuit means includes fast and slow potentiometer means operatively connected to said ramp function generator wherein the generator field voltage drop can be set at different valves for different speeds of the shear means 5. The machine of claim 1 wherein said counter means is connected to said feed roll means the surface speed of which is proportional to the speed of said flying shear means; said counter means also including a connection with said flying shear means by which counting is commenced on closing of the blades of said flying shear means.

6. The machine of claim 5 further including pinch rolls removed from said-feed rolls, said detection means being intermediate said pinch roll and feed rolls; second control means for said drive means, said second control means being mechanically connected to the control means for the shear and feed roll drive means so that the speed of the pinch rolls is proportional to the speed of the shear and feed roll drive means. 

